Jothiraj, Walter (McGill University), Sharf, Inna (McGill University), Nahon, Meyer (McGill University)

Control Allocation of Bidirectional Thrust Quadrotor Subject to Actuator Constraints

Scheduled for presentation during the Regular Session "Micro- and Mini- UAS I" (ThB4), Thursday, September 3, 2020, 15:00−15:20, Naousa

2020 International Conference on Unmanned Aircraft Systems (ICUAS), September 1-4, 2020 (Postponed from June 9-12, 2020), Athens, Greece

This information is tentative and subject to change. Compiled on April 26, 2024

Abstract

In this paper, we work with a quadrotor vehicle capable of producing bidirectional thrust by reversing the rotation of its propellers. These vehicles have a number of unique functions, such as inverted hover, faster than gravity acceleration for descent and, generally, superior agility compared to their unidirectional conventional designs. However, thrust reversal presents a set of unique challenges for controlling these vehicles due to the particular transient dynamics of the propellers as they transition from positive to negative rotation. To deal with the limitations of bidirectional actuators, we propose an optimal control allocation strategy that produces the best match to the desired force and moments prescribed by the controller, while respecting the limits on actuator thrusts and their rate of change. The latter are identified through transient response characterization of the bidirectional propellers. The optimal allocation is evaluated in simulation for a half-flip maneuver between upright and inverted hover. Outdoor flight tests demonstrate the superior performance of the optimal solution as compared to direct allocation commonly used in flight controllers of quadrotors.